Outline

Objective: A circumscribed small amount of subarachnoid blood in a pre-pontine localization is a finding which triggers questions concerning the diagnostic work-up as well as the therapeutic consequences. Literature says that one hardly detects a precise cause for the actual bleeding, rendering therapeutic approaches rather questionable.

Methods: This study covers the investigation of 135 consecutive patients, admitted to our hospital with an acute SAH during a five year period. The patients presenting with a limited pre-pontine SAH received a DS-angiography (Integris-5000, Philips) as well as a MD-CT-angiography (Aquilion-64, Toshiba) to determine the bleeding cause. Both investigation techniques were compared to one another in terms of detecting an aneurysm, an AV-malformation, a vascular spasm or other associated pathologies.

Results: Out of 135 patients presenting with an acute SAH, in 27 patients (20%) a limited pre-pontine SAH was discovered. The patients presented with a mean GCS of 10.4 (14–6) and a Hunt&Hess state of 1.8 (1–4). In all 27 patients a DSA and an MSCTA was technically feasible. A control study was performed between 12 days and 2 weeks later. The average time to perform the diagnostic procedures took 55 minutes for the DSA, while MSCTA took 12 minutes. While the DSA procedure caused one complication with a temporary hemiparesis resolving after two weeks, MSCTA showed none.

With neither modality we discovered an aneurysm or an AVM responsible for the SAH. The control studies after 2 weeks and 6 months were also negative.

DSA demonstrated vasospasm in 6 patients (22%), while CTA revealed spasm in only 3 patients (11%). On the other hand, MSCTA is superior in detecting associate pathologies like intraparenchymal – 1 patient (4%) – and intraventricular bleeding – two patients (7%) – or an evolving hydrocephalus – three patients (11%).

Conclusions: In all 27 cases of a cryptic pre-pontine SAH neither DSA, nor MSCTA could reveal a definitive bleeding cause. Neither an aneurysm, nor an AVM was found.

DSA has a higher sensitivity in finding vasospasm, while MSCT is to be preferred in detecting concomitant pathologies like intraparenchymal and intraventricular bleeding or an evolving hydrocephalus.

We suggest a combined diagnostic workup of a cryptic pre-pontine SAH: 1) Initial MSCTA after diagnosing an SAH, 2) DSA after 12–14 days and 3) MSCTA-control study after 4–6 months, given the preceding angiography is negative.